PHENIX measurements of 3D emission source functions in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV

Abstract

A state-of-the-art 3D source imaging technique is used to extract the 3D two-pion source function in central and mid-central Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. The source function indicates a previously unresolved non-Gaussian tail in the directions of the pion pair transverse momentum (out) and along the beam (long). Model comparisons give robust estimates for several characteristics of the emission source, including its transverse size, its mean proper breakup time $\tau$ and its emission duration $\Delta\tau$. These estimates are incompatible with the predictions for a first order phase transition. However, they point to significant relative emission times which could result from a crossover phase transition.